Chamber stability monitoring using an integrated metrology tool

ABSTRACT

A method and apparatus for monitoring the stability of a substrate processing chamber and for adjusting the process recipe. Thickness and CD measurement data are collected before wafer processing and after wafer processing by an integrated or an in-situ metrology tool to monitor process chamber stability and to adjust the process recipe. The real time chamber stability monitoring enabled by the integrated metrology tool reduces the risk and cost of wafer mis-processing. The real time process recipe adjustment allows tightening of the process recipe. Process development cycle can also be reduced by the method and apparatus.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to semiconductor substrate processingsystems. More particularly, the present invention relates to techniquesfor monitoring the chamber stability and, in response, adjusting aprocess recipe to optimize substrate processing.

2. Description of the Related Art

Current demands for high density and performance associated with ultralarge scale integration require sub-micron features, increasedtransistor and circuit speeds and improved reliability. Such demandsrequire formation of device features with high precision and uniformity,which in turn necessitates careful process monitoring, includingfrequent and detailed inspections of the devices before thesemiconductor wafers are diced into individual circuit chips.

Early detection of chamber fault or process drift is highly desirable,since it can prevent wafer mis-processing, which in turn reduces waferscrapping, wafer rework and overall device production cost. In thefabrication of active and passive electronic devices on a substrate, atypical substrate has conducting, semiconducting, and dielectricfeatures that form or interconnect the devices on the substrate.Typically, the material is formed on the substrate by, for example, achemical vapor deposition (CVD), physical vapor deposition, ionimplantation, oxidation or nitridation process. Thereafter, some of thesubstrate materials, which are generally in the form of a layer but mayalso have other shapes, may be processed, for example by etching, toform features shaped as cavities, channels, holes, vias or trenches.

As technology advances, it requires smaller feature sizes and tighterfeature space to improve device performance and to achieve higher devicedensity. It may also be desirable to etch deep features having highaspect ratio to provide faster circuits or otherwise higher signalprocessing efficiency. The aspect ratio of the feature is the ratio ofthe feature depth to its opening size. One example of feature patterningis silicon deep trench etch for DRAM trench capacitor fabrication.

In DRAM silicon deep trench capacitor fabrication, the opening size ofthe trenches may be less than about 0.14 microns and the depth of thetrenches may be greater than 7 microns. The aspect ratio of these deeptrenches could be higher than 50. It is difficult to etch featureshaving high aspect ratio using conventional substrate processingtechniques, especially when the features also have small opening sizes.This high aspect ratio trench etch process is generally sensitive tochanges in the process chamber condition and to the sizes of theopening. Chamber condition can greatly affect plasma state and reactantconcentration. It is difficult for reactants to penetrate deep into thetrench through small openings and difficult for reaction by-products tobe transported from inside the trench back out to the substrate surfacethrough the same small openings.

Therefore, there is a need in the art for techniques of monitoring theprocess conditions of a process chamber to facilitate adapting theprocess recipe to the process conditions such that the substrateprocessing is improved.

SUMMARY OF THE INVENTION

The invention relates to a method and apparatus for monitoring thestability of a process chamber by measuring characteristics of materiallayers on a substrate with an integrated metrology tool. The inventiontrends the calculated process rate, which could include etch rate anddeposition rate, of each wafer processed by the process chamber bymeasuring the film thickness on the substrate before and after substrateprocessing, and by recording the total process time to detect anyprocess drift to prevent substrate mis-processing. The invention alsoutilizes the trended process rate and pre-process thickness measurementof the incoming wafer in adjusting the process recipe in real time totighten the process control. Lastly, the invention also shortens processdevelopment cycle time by utilizing real time process information.

Embodiments of the invention provide a method of using an integratedmetrology tool to monitor substrate processing that occurs in aprocessing chamber. The method includes placing the substrate in anintegrated metrology tool before the substrate enters the processingchamber, collecting measurement data prior to substrate processing usingthe integrated metrology tool, moving the substrate into the processingchamber, processing the substrate in the processing chamber, recordingthe total processing time, placing the substrate in the integratedmetrology tool after the substrate processing is completed, andcollecting measurement data after substrate processing using theintegrated metrology tool.

Another embodiment of the invention provides a method of adjusting aprocess recipe used by a processing chamber to process a substrate. Themethod includes placing the substrate in an integrated metrology toolbefore the substrate enters the processing chamber, collectingmeasurement data prior to substrate processing, in the integratedmetrology tool, moving the substrate into the processing chamber, andadjusting the process recipe in real time in the processing chamberbased on the pre-process measurement and a process rate trend.

In a further embodiment, the method of the invention calculates aprocess rate by manipulating the pre-processing thickness measurement,post-processing thickness measurement and the total processing time,trending the process rate, comparing the process rate trend with acontrolling algorithm, and signaling detection of a performance drift ifthe data triggers the process controlling algorithm.

Embodiments of the invention may further provide an apparatus formonitoring a process chamber and for adjusting the process recipe inreal time during substrate processing within the process chamber. Theapparatus includes a process chamber, a metrology tool for measuringfilm thickness and critical dimension (CD) information that is coupledto the process chamber, a computer system for calculating the processrate, storing thickness and CD measurement and process rate information.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features of the invention describedherein are attained and can be understood in detail, a more particulardescription of the invention, briefly summarized above, may be had byreference to the embodiments thereof which are illustrated in theappended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1 is a cross-sectional diagram of a patterned wafer prior to highaspect ratio deep trench etch processing.

FIGS. 2 a and 2 b are cross-sectional diagrams of a silicon deep trenchetch under “normal” chamber condition. FIG. 2 a shows the etchingactivities of reactant species (R) and the passivating function ofby-product species (B). FIG. 2 b shows a deep trench profile (normal)after silicon deep trench etch.

FIGS. 3 a and 3 b are cross-sectional diagrams of a silicon deep trenchetch under “abnormal” chamber condition. FIG. 3 a shows the limitedetching activities of reactant species (R) in the trench, excess etchingof the BSG layer, and the limited availability of by-product species (B)to passivate the top BSG layer. FIG. 3 b shows a deep trench profile(pinched-off) after silicon deep trench etch.

FIG. 4 is an etch rate trend graph for a silicon etch chamber.

FIG. 5 is a schematic diagram of wafer movement and metrology datacollection of wafers processed through an etch chamber that is notintegrated with a metrology tool.

FIG. 6 is a schematic diagram of wafer movement and metrology datacollection of wafers processed through an etch chamber that isintegrated with a metrology tool.

FIG. 7 is a block diagram of key components of an integrated etchsystem.

FIG. 8 is a diagram of one embodiment of an integrated etch system.

DETAILED DESCRIPTION

Semiconductor device fabrication requires feature patterning. When thedevice being fabricated is a DRAM, one step in the device fabricationprocess is silicon deep trench etching to form trench capacitors. Thepresent invention is a method and apparatus that finds use in devicefabrication and is especially useful in deep trench etching.

More specifically, the invention measures the thickness of a materiallayer on a substrate using an integrated metrology tool that is coupledto a substrate processing chamber (e.g., a deep trench etch system). Themeasurement data are utilized and tracked by the substrate-processingchamber to adjust a process recipe in real time, and to detect processdrift. As such, the real time adjustment of the process recipefacilitates accurate processing of the substrate. The real time processinformation also assists in shortening the process development cycle.

For convenience, the present invention is described herein primarilywith reference to deep silicon trench etch for DRAM trench capacitorpreparation. The invention can be used for other types semiconductorsubstrate preparation processes, including, but not limited to, otheretch processes and deposition processes. Details of a high aspect ratiotrench (HART) etcher and etching chemistry that are used to etch deepsilicon trenches for this application have been disclosed in commonlyassigned U.S. patent application Ser. Nos. 09/704,887 and 09/705,254,both titled “Etching of High Aspect Ratio Features in a Substrate”, andboth filed on Nov. 1, 2000.

FIG. 1 shows a cross-sectional diagram of one embodiment of a patternedwafer 100 prior to high aspect ratio deep trench silicon etch. Thepatterning stack 108 that defines the location of a trench to be formedmay include 7000 Å to 1 μm BSG (borosilica glass) 102, 2000 Å of siliconnitride 104, and 100 Å of pad oxide 106. The patterning stack 108 isplaced on top of a bare silicon surface 112. In FIG. 1, the patterningstack 108 has already been opened using a conventional patterningprocess to form gap 110 and is ready for silicon deep trench etch. Thereactants used to etch a deep trench in silicon generally involve acombination of one or more gases including SF₆, HBr, NF₃, O₂ (or He—O₂),Cl2, Br₂, other Halogen-based compound, SiF₄, C₄F₈, other fluorocarbon(C_(x)F_(y)) and hydrofluorocarbon (HFC or C_(x)H_(y)F_(z)). The silicondeep trench etching process is relatively sensitive to changes in theprocess chamber, such as changes in chamber pressure, gas flow,by-product re-deposition on the chamber wall, chamber temperature, andsubstrate temperature. In one study involving O₂ as one of the reactivegases that produces a passivating by-product, such as SiO₂ orSiO_(x)Br_(y), a mere 4-5% reduction in O₂ flow rate (e.g. 2/50 sccm)could move the process into an un-operable regime. The silicon deeptrench etching process is also relatively sensitive to the size ofopening for sub-0.14 μm device manufacturing. If the process is designedfor processing 0.14 μm targeted CDs (critical dimensions) and incomingsubstrates have trench openings that average significantly below 0.14 μm(e.g., an average of 0.12 μm), the process might not be able to etch thetrenches to the depth of 6-7 μm. Details of how to use an integrated CDmetrology tool to gather and utilize pre-etch and post-etch CDs anddevice feature profiles of wafers going through the etch chamber havebeen disclosed in commonly assigned U.S. Pat. No. 6,486,492, titled“Integrated Critical Dimension Control for Semiconductor DeviceManufacturing”, issued on Nov. 26, 2002, U.S. Pat. No. 6,388,253, alsotitled “Integrated Critical Dimension Control for Semiconductor DeviceManufacturing”, issued on May, 14, 2002, and U.S. application Ser. No.10/428,145, titled “Method and Apparatus for Controlling Etch ProcessesDuring Fabrication of Semiconductor Devices”, filed on May 1, 2003.Details of how to use an in-situ CD metrology tool to gather CD datahave been disclosed in commonly assigned U.S. application Ser. No.60/479,601, titled “Method and System for Monitoring an Etch Process”,filed on Jun. 18, 2003. Device feature profiles and CDs can be usedtogether to fine tune the etch recipe.

FIG. 2A shows the surface reaction of silicon deep trench etch when theetch chamber is operated under a normal (or “good”) condition, such ascorrect gas flow control and substrate temperature, etc., and the CDs ofthe trench openings 210 are not outside the control limit. Reactants (R)are distributed across the substrate surface 212 and trench 210 surfaceto etch the surface 212 of the BSG mask layer 204 and also the siliconsurface 214 in the trench. The by-products (B) generated from theetching process, such as SiO₂, would escape from the trench 210 topassivate the BSG mask surface 212 and would slow the BSG mask etchrate. FIG. 2B shows the post etch silicon trench profile 250. Thepost-etch BSG thickness 252 is thinner than pre-etch thickness 202, buta sufficient amount, such as 1000-2000 Å is still left, as planned.

On the other hand, when the chamber condition is abnormal, such as outof specification chamber pressure, or when the wafer CDs are below thecontrol limit, the reactants (R) cannot reach deep into trench 310 tofurther the etching process (see FIG. 3A). The abnormal chambercondition can result in by-product (B) buildup at the silicon trenchsurface 314 that prohibit reactant (R) from etching the silicon surface,which can cause the trench to show a pinch-off shape. Since thereactants (R) cannot be distributed across the silicon trench surface314 to etch silicon, higher amount of reactants (R) are available toetch BSG surface 312 and increases its etch rate. In addition, sinceless silicon etch occurs in the trench 310, fewer by-products (B) areavailable to redeposit on the substrate surface 312 (also BSG surface)to slow down the BSG etch rate. The net result is a much thinner BSG 352or no remaining BSG after etch (see FIG. 3B).

By subtracting the post-etch BSG thickness from the pre-etch BSGthickness, the BSG etch rate can be calculated and the health of theetch performance can be monitored. A significant increase in BSG etchrate could signal a process drift that is caused by chamber abnormalityor wafer CDs that are lower than the CD specification. The cause ofsignificant BSG etch rate increase by lower than specified wafer CDs canbe ruled out by examining the pre-etch wafer CDs measurement using anintegrated CD metrology tool described above. The thickness measurement,CD measurement and device feature profiles can be performed in the samemetrology tool that utilizes optical scatterometry or reflectometry. Thethickness measurement and CD measurement could also be conducted inseparate, but integrated, metrology tools. The concept of this inventioncan also be extended to other film characterization tools, such as FTIR(Fourier-Transform Infra-Red) for film composition analysis.

FIG. 4 shows a BSG etch rate trend graph 400. The X-axis represents thesequence of wafers 402 that have been monitored for etch rate. Thewafers on the left are processed before wafers on the right. For wafersprocessed in a silicon deep trench etcher with an integrated metrologytool(s), ideally every wafer is monitored for BSG etch rate. However,this is not necessary. Monitoring every other wafer or every few wafersis also acceptable. The Y-axis represents the BSG etch rate 404, whichis calculated by subtracting post-etch thickness from pre-etch thicknessand then dividing the net value by the etch process time. The BSG etchrate of wafers that begin processing having within specification CDs andare processed under “normal” chamber condition, are expected to fallwithin upper control limit (UCL) and lower control limit (LCL). Thegraph 400 represents process drift beginning at wafer A when the BSGetch rate of wafer A rises slightly above the process trend. The BSGetch rate trend after wafer A continues to rise and exceeds the UCL forwafer B. Wafers processed after wafer A have the risk of having apinched-off trench profile and might need to be scrapped. Wafersprocessed after wafer B will likely be scrapped.

Traditionally, a deposition or etch chamber is not integrated with ametrology tool (see FIG. 5). For an etch process chamber that is notintegrated with a metrology tool 500, the delay time would be long totransport wafers (wafer cassette 506) from metrology tool 504 to etchtool 508. Then the wafer cassette 510 is transported back to themetrology tool 504. Precious time is wasted in moving the wafer box (orcassette) and also in waiting for the cassette to be moved through aqueue. Typically only a couple of wafers from each lot 502 are selectedto measure post-etch critical dimensions (CDs) to make sure that the CDsmeet the specification. Patterning stack thickness is typically notmonitored. This is due to concern over delay caused by additional wafermovement and queue time to take the measurement at a non-integratedmetrology tool. If wafers were confirmed to have suffered from deeptrench pinch-off problem at a later stage by cross-section SEM and thecause is confirmed to be due to chamber abnormality, many lots of wafersprocessed before the problem is identified would likely need to bescrapped. The cost of the scrapped wafers could be very high. Even ifselected wafers of a processed lot are measured for BSG post-etchthickness to check for chamber stability, since the metrology tool isnot integrated, several lots could be processed before the measurementresults are obtained. As such, the risk of not identifying the processdrift immediately still exists.

On the other hand, when an etcher 606 is integrated with an ex-situmetrology tool 604 or an in-situ metrology tool 610 to form anintegrated system 608, as shown in FIG. 6, no time will be wasted onphysical movement of the cassette and waiting in a queue. The integratedsystem 608 allows measuring BSG thickness before and after processingfor every wafer going through the etch chamber at no additional cost ofwafer throughput. Deep trench etching of 6-7 μm silicon can take between5 to 10 minutes per wafer, while a 9-point thickness measurement usingan optical-scatterometry-based metrology tool would take less than 2minutes. The thickness measurement time could further be lowered byreducing the number of measurement sites (points). The data gathered bythe metrology tool can be instantly fed to a data processor connected tothe etch chamber. Consequently, there may be no impact on waferprocessing throughput.

An exemplary embodiment of the present invention is implemented using anex-situ metrology tool 710 (measurement tool) in a processing line 700,as shown in FIG. 7, comprising a measuring tool 710, e.g., an opticalmetrology tool such as Nano OCD 9000 available from Nanometrics ofMilpitas, Calif. The metrology tool 710 can utilize scatterometry orreflectometry techniques. The use of scatterometry for inspection andmetrology tools is disclosed in Raymond, “Angle-resolved scatterometryfor semiconductor manufacturing”, Microlithography World, Winter 2000.The use of reflectometry for inspection and metrology tool is taught inLee, “Analysis of Reflectometry and Ellipsometry Data from PatternedStructures”, Characterization and Metrology for ULSI Technology: 1998International Conference, The American Institute of Physics 1998. Othermetrology and/or wafer inspection techniques may be used. The processingline 700 further comprises a processor 720, which performs the analysisdisclosed herein electronically, and a monitor 730 for displayingresults of the analysis of the processor 720. The processor 720 can bein communication with a memory device 740, such as a semiconductormemory, and a computer software-implemented database system 750, knownas a “manufacturing execution system” (MES) conventionally used forstorage of process information.

An example of an etch system that is integrated with an ex-situmetrology tool with the capability of measuring CDs and film thicknessis Applied Materials' Transforma system 800 (FIG. 8). Detailedinformation describing Applied Materials' Transforma system has beendisclosed in a commonly assigned U.S. patent application Ser. No.10/428,145, titled “Method and Apparatus for Controlling Etch ProcessesDuring Fabrication of Semiconductor Devices”, filed on May 1, 2003. Thesystem comprises a chamber or “mainframe” 801, such as the Centura™processing system for mounting a plurality of processing chambers, e.g.,conventional etch reactors 802, such as DPSII™ silicon etch chambers andone or more transfer chambers 803, also called “load locks”. In oneembodiment of the present invention, four etch reactors 802 are mountedto the mainframe 801. In one exemplary embodiment, three etchers 802 areused for etching and one is optionally used for post-etch cleaning (i.e.removing photoresist polymers and other residue from wafers afteretching). A robot 804 is provided within the mainframe 801 fortransferring wafers between the processing reactors 802 and the transferchambers 803. The transfer chambers 803 are connected to a factoryinterface 805, also known as a “mini environment”, which maintains acontrolled environment. A metrology (or measurement) tool 806 could beintegrated in the load lock area 805 and with high-speed data collectionand analysis capabilities, every wafer that enters the system 800 can bemeasured for thickness before and after etch processing. The metrologytool 806 could also be placed at different location within the processsystem 800. One or more of the process chambers 802 could also bedeposition chambers, since the concept of the invention also applies todeposition process.

The operation of the apparatus according to this embodiment of thepresent invention will now be described with reference to the flow chartof FIG. 9. After the wafers are processed at a processing tool to form aphotoresist mask on an underlying layer, they are loaded into thecassette 808, and the cassette is transferred to a factory interface 805at step 902. A wafer is then unloaded from the cassette 808 andtransferred to the metrology tool 806 using a robot 807 (step 904). Atstep 906, the thickness of the film, the CDs, and device featureprofiles are collected. At step 908, an etch recipe for the wafer isadjusted based on the thickness measurement, the CDs, and device featureprofiles, as explained above. At step 910, the wafer is transferred fromthe metrology tool 806 to the etcher 802 using the robot 807 to move thewafer to the transfer chamber 803, and using the robot 804 to move thewafer to the etcher 802. At step 912, the wafer undergoes a silicon deeptrench etch according to the recipe. The wafer is then transferred backto the metrology tool 806 for a post-etch CD measurement, device featureprofiles and a thickness measurement before being loaded into thecassette 808 at step 918. The thickness measurement, and post etch CDs,and device feature profiles are coupled to the processor 720, and usedto calculate BSG etch rate and/or to correct etch recipe for the nextwafer to be etched, as explained above. Detailed information of how toadjust etch recipe is described in a commonly assigned U.S. patentapplication Ser. No. 10/428,145, titled “Method and Apparatus forControlling Etch Processes During Fabrication of Semiconductor Devices”,filed on May 1, 2003.

An example of an in-situ metrology tool 610, described in FIG. 6, withthe capability of measuring CDs and film thickness is the EyeD™metrology module, available from Applied Materials of Santa Clara,Calif. The EyeD™ metrology module may use one of more non-destructiveoptical measuring techniques, such as spectroscopy, interferometry,scatterometry, reflectometry, and the like. The in-situ metrology toolmay be, for example, configured to perform an interferometric monitoringtechnique (e.g., counting interference fringes in the time domain,measuring position of the fringes in the frequency domain, and the like)to measure the etch depth profile of the structure being formed on thesubstrate in real time. Details of how to use an in-situ CD metrologytool to gather CD data have been disclosed in commonly assigned U.S.application Ser. No. 60/479,601, titled “Method and System forMonitoring an Etch Process”, filed on Jun. 18, 2003. Device featureprofiles and CDs can be used together to fine tune the etch recipe.Details of how to use an in-situ thickness metrology tool to gatherthickness data have been disclosed in commonly assigned U.S. Pat. No.6,413,837, titled “Film Thickness Control Using SpectralInterferometry”, issued on Jul. 2, 2002, and U.S. application Ser. No.60/462,493, titled “Process Control Enhancement and Fault DetectionUsing In-Situ and Ex-situ Metrologies and Data Retrieval In MultiplePass Wafer Processing, filed on Apr. 11, 2003.

FIG. 10 is a simplified cross-sectional view of an exemplary plasma etchchamber 1000 configured to practice the method of present invention. Asshown in FIG. 10, etch chamber 1000 includes a housing 1012 thatsurrounds a substrate processing region 1014. During an etch process asubstrate 1018 is supported on a pedestal 1016 and exposed to a plasmaformed in region 1014. The plasma generates electromagnetic radiationthat includes emissions having wavelengths in the optical spectrum(i.e., from about 180 to 1100 nm). A portion of these emissions arereflected from the surface of substrate 1018 and through a window 1020so they can be measured by the spectrometer 1022. A folding mirror 1024reflects the radiation that passes through the window 1020 towards alens 1026 that collimates the radiation into a fiber optic cable 1028.The fiber optic cable 1028 is the vehicle through which the radiationtravels to reach the spectrometer 1022. The folding mirror 1024 and thelens 1026 are positioned so that radiation reflected from the uppersurface of the substrate 1018 passes through the window 1020 verticallyinto the optical fiber 1028. Placement of the window 1020 above thesubstrate 1018 as shown in FIG. 1 allows better resolution of themeasured radiation as opposed to placement of the window on the side ofthe chamber but other embodiments may position window 1020 on thechamber side.

In embodiments that employ a broadband light source 1034 in addition toor instead of the plasma emission, the fiber optic cable 1028 is abifurcated cable. In these embodiments, the light source 1034 isoptically coupled to one of the channels of the bifurcated cable 1028and the spectrometer 1022 is coupled to the other channel. Light fromthe broadband light source 1034, e.g., a mercury, deuterium or xenonlamp, travels along one channel of the cable 28 through the window 1020and is reflected from the substrate 1018. The reflected light passesthrough the window 1020 into the other channel of the cable 1028 asdescribed above before finally reaching the spectrometer 1022. Thespectrometer 1022 spectrally separates radiation based on wavelength(e.g., via a prism or diffraction grating), and generates detectionsignals (e.g., detection currents) for a plurality of the spatiallyseparated wavelengths. A data acquisition card 1030 is coupled to aprocessor 1032 to collect and process data representing the separatedwavelengths. The data is collected at a periodic sampling rate by thedata acquisition card 1030 and each sample is processed by the processor1032. In one embodiment, the processor 1032 also controls the operationof chamber 1000 by executing computer instructions stored in a memory1031 coupled to the processor.

The operation of the apparatus according to this embodiment of thepresent invention will now be described with reference to the flow chartof FIG. 11. After the wafers are processed at a processing tool to forma photoresist mask on an underlying layer, the wafers are loaded intothe cassette 808, and the cassette is transferred to a factory interface805 at 1102. At step 1104, a wafer is then unloaded from the cassette808 and transferred to the etcher 802 using robot 807 to move the waferto the transfer chamber 803, and using the robot 804 to move the waferto etcher 802. At step 1106, the thickness of the film, the CDs, anddevice feature profiles are collected. At step 1108, an etch recipe forthe wafer is adjusted based on the thickness measurement, the CDs andthe device feature profiles, as explained above. At step 1110, the waferundergoes a silicon deep trench etch according to the recipe. At step1112, the post-etch thickness of the film, the CDs, and device featureprofiles are collected again. The thickness measurement, the post etchCDs, and device feature profiles are coupled to the processor 1031, andused to calculate BSG etch rate and/or to correct etch recipe for thenext wafer to be etched, as explained above. Afterwards, the wafer istransferred back to the cassette at step 1114.

Film thickness, CDs, and device feature profiles can also be collectedcontinuously during the etching process to instantaneously adjust theetch recipe until the targeted thickness or CD is reached. This processis shown in FIG. 12. The steps in FIG. 12 have similar functions tosteps in FIG. 11. In the process flow of FIG. 12, there is an additionaldecision making step 1213 to determine if the targeted thickness or CDhas been reached or not. If the targeted thickness or CD has not beenreached, the process step loops back to step 1208 until the targetedthickness or CD has been reached.

The integrated metrology system solves the delay problems caused bywafer transportation time and queue wait time. It has other advantagesover a traditional etch chamber that is not integrated with a metrologytool. For example, the pre-etch and post-etch measurement of aparticular wafer can be tracked to calculate the etch rate of theparticular wafer to reflect a more accurate chamber performance,compared to the sampled post-etch thickness monitoring. Furthermore,since performance of every wafer is instantly tracked, indications of aprocess drift can be alerted to an operator instantly to take immediateaction. This would prevent mis-processing of following wafers andunnecessary wafer scrapping. Since the measurement tool also has thecapability of measuring wafer CDs, concerns over lower thanspecification causing higher BSG etch rate could be ruled out byexamining the pre-etch wafer CDs. In addition, the pre-etch measurement,e.g. CDs, device feature profile, and optionally BSG thickness, can befed-forward to the etch chamber that utilizes the etch chamberperformance trends, such as etch rate and CD trends, to adjust etchrecipe for each individual wafer for best etch performance and processcontrol. Lastly, the instant tracking and revealing of etch results bythe integrated data processor can greatly reduce the etch processdevelopment time. In contrast, development conducted in a non-integratedsystem is relatively slow, since the data collection is very timeconsuming.

The invention can also be applied to other process chambers, such asdeposition chambers. The metrology tool described as being used in oneembodiment of the invention can also be other types of filmcharacterization tools, such as FTIR (Fourier-Transform Infra-Red) forfilm composition analysis.

Accordingly, while the present invention has been disclosed inconnection with various embodiments thereof, it should be understoodthat other embodiments might fall within the spirit and scope of theinvention, as defined by the following claims.

1. A method of monitoring a process performed by a processing chamber,comprising: placing a substrate in an integrated metrology tool beforethe substrate enters the processing chamber; collecting pre-processmeasurement data prior to substrate processing using the integratedmetrology tool; moving the substrate into the processing chamber;processing the substrate in the processing chamber; recording a totalprocessing time; moving the substrate into the integrated metrology toolafter the substrate processing is completed; and collecting post-processmeasurement data after substrate processing using the integratedmetrology tool.
 2. The method of claim 1, further comprising:calculating a process rate using the pre-process measurement data,post-process measurement data and the total processing time; computing aprocess rate trend; comparing the process rate trend to a limit level;and signaling detection of a performance drift when the process ratetrend exceeds the limit level.
 3. The method of claim 2, wherein theprocessing chamber is an etch chamber.
 4. The method of claim 2, whereinthe processing chamber is a deposition chamber.
 5. The method of claim3, wherein the pre-process measurement data and post-process measurementdata include both thickness measurement and critical dimensioninformation.
 6. The method of claim 5, further comprising: examining apre-etch critical dimension information; and excluding a contribution ofthe critical dimension of a feature as a cause of the process drift, ifthe pre-etch critical dimension information is complies with apre-defined critical dimension specification.
 7. The method of claim 1wherein the moving steps are performed within a vacuum.
 8. The method ofclaim 1 wherein the integrated metrology tool performs at least one ofscatterometry and reflectometry to produce pre-process and post-processmeasurement data.
 9. A method of adjusting a process recipe in aprocessing chamber, comprising: placing the substrate in an integratedmetrology tool before the substrate enters the processing chamber;collecting pre-process measurement data prior to substrate processing,using the integrated metrology tool; moving the substrate into theprocessing chamber; and adjusting, in real time, the process recipe usedby the processing chamber to process the substrate based on thepre-process measurement data and a process rate trend.
 10. The method ofclaim 9, wherein the processing chamber is an etch chamber and theprocess rate trend is a etch rate trend.
 11. The method of claim 9,wherein the processing chamber is a deposition chamber and the processrate trend is a deposition rate trend.
 12. The method of claim 9 whereinthe moving step is performed in a vacuum.
 13. The method of claim 9wherein the integrated metrology tool performs at least one ofscatterometry and reflectometry to produce pre-process measurement data.14. A method of monitoring a process performed by a processing chamber,comprising: moving a substrate into the process chamber; collectingpre-process measurement data prior to substrate processing using anin-situ metrology tool; processing the substrate in the processingchamber; recording a total processing time; and collecting post-processmeasurement data after substrate processing using the in-situ metrologytool.
 15. The method of claim 14, further comprising: calculating aprocess rate using the pre-process measurement data, post-processmeasurement data and the total processing time; computing a process ratetrend; comparing the process rate trend to a limit level; and signalingdetection of a performance drift when the process rate trend exceeds thelimit level.
 16. The method of claim 15, wherein the processing chamberis an etch chamber.
 17. The method of claim 15, wherein the processingchamber is a deposition chamber.
 18. The method of claim 16, wherein thepre-process measurement data and post-process measurement data includeboth thickness measurement and critical dimension information.
 19. Themethod of claim 18, further comprising: examining a pre-etch criticaldimension information; and excluding a contribution of the criticaldimension of a feature as a cause of the process drift, if the pre-etchcritical dimension information is complies with a pre-defined criticaldimension specification.
 20. The method of claim 14 wherein the movingsteps are performed within a vacuum.
 21. The method of claim 14 whereinthe integrated metrology tool performs at least one of scatterometry andreflectometry to produce pre-process and post-process measurement data.22. A method of adjusting a process recipe in a processing chamber,comprising: moving a substrate into the process chamber; collectingpre-process measurement data prior to substrate processing, using thein-situ metrology tool; and adjusting, in real time, the process recipeused by the processing chamber to process the substrate based on thepre-process measurement data and a process rate trend.
 23. The method ofclaim 22, wherein the processing chamber is an etch chamber and theprocess rate trend is a etch rate trend.
 24. The method of claim 22,wherein the processing chamber is a deposition chamber and the processrate trend is a deposition rate trend.
 25. The method of claim 22wherein the moving step is performed in a vacuum.
 26. The method ofclaim 22 wherein the integrated metrology tool performs at least one ofscatterometry and reflectometry to produce pre-process measurement data.27. Apparatus for processing a substrate, comprising: a process chamberfor processing a substrate; a metrology tool for measuring filmthickness and critical dimension information of the substrate prior toand after processing by the process chamber; and a computer system,coupled to the process chamber and the measurement tool, for calculatinga process rate and process trend information, and storing the filmthickness and critical dimension information.
 28. The apparatus in claim27, wherein the process chamber is an etch chamber.
 29. The apparatus inclaim 27, wherein the process chamber is a deposition chamber.
 30. Theapparatus in claim 28, wherein the metrology tool is capable ofmeasuring thickness, critical dimensions and device feature profile. 31.The apparatus in claim 29, wherein the metrology tool is capable ofmeasuring film thickness of a film on the substrate.
 32. The apparatusin claim 27, wherein the metrology tool is an integrated with theprocess chamber and ex-situ to the process chamber.
 33. The apparatus inclaim 27, wherein the metrology tool is in-situ to the process chamber.34. The apparatus of claim 32 further comprising a mainframe having arobot for moving the substrate between the metrology tool and theprocessing chamber within a vacuum.
 35. The apparatus of claim 27wherein the metrology tool performs at least one of scatterometry andreflectometry.